As the usage of the Internet expands and many new types of services are provided on the Internet, the Internet is moving toward a service-centric model. Accompanying this trend, more and more storage and computational resources are being put into the network infrastructure of the Internet for providing services to customers. For instance, in the past few years, there has been a tremendous amount of investments in developing content delivery networks (CDNs) as a network overlay infrastructure service available to content providers and network access providers (e.g., ISPs). The content delivery networks provide a large number of caches and storage devices installed in servers located at the edge of the Internet network structure for pushing contents at a point closer to the content consumer, thereby allowing fast and reliable content delivery.
In addition to improved content delivery, content providers and consumers are interested in value-added services that operate on the content (or the content request) on its way between the content origin (e.g., a Web site) and the content consumer. Such services are often referred to as “content-oriented services” (or sometimes “content services”) and include, for example, content adaptation, content personalization, watermarking, location-aware data insertion, etc. The edge servers of the content delivery network, being already positioned in the content delivery paths, offer a natural place to extend the capability of network intermediaries to provide content-oriented services. There are, however, many challenging issues in designing a framework for such a network for content-oriented services that have to be resolved. For instance, one main issue is how to make the services available to those who want to use the services, and another related main issue is how to ensure that the content sent or requested by a customer of the services will receive the intended processing.